One-dimensional self-assembly of planar pi-conjugated molecules: adaptable building blocks for organic nanodevices

In general, fabrication of well-defined organic nanowires or nanobelts with controllable size and morphology is not as advanced as for their inorganic counterparts. Whereas inorganic nanowires are widely exploited in optoelectronic nanodevices, there remains considerable untapped potential in the one-dimensional (1D) organic materials. This Account describes our recent progress and discoveries in the field of 1D self-assembly of planar pi-conjugated molecules and their application in various nanodevices including the optical and electrical sensors. The Account is aimed at providing new insights into how to combine elements of molecular design and engineering with materials fabrication to achieve properties and functions that are desirable for nanoscale optoelectronic applications. The goal of our research program is to advance the knowledge and develop a deeper understanding in the frontier area of 1D organic nanomaterials, for which several basic questions will be addressed: (1) How can one control and optimize the molecular arrangement by modifying the molecular structure? (2) What processing factors affect self-assembly and the final morphology of the fabricated nanomaterials; how can these factors be controlled to achieve the desired 1D nanomaterials, for example, nanowires or nanobelts? (3) How do the optoelectronic properties (e.g., emission, exciton migration, and charge transport) of the assembled materials depend on the molecular arrangement and the intermolecular interactions? (4) How can the inherent optoelectronic properties of the nanomaterials be correlated with applications in sensing, switching, and other types of optoelectronic devices? The results presented demonstrate the feasibility of controlling the morphology and molecular organization of 1D organic nanomaterials. Two types of molecules have been employed to explore the 1D self-assembly and the application in optoelectronic sensing: one is perylene tetracarboxylic diimide (PTCDI, n-type) and the other is arylene ethynylene macrocycle (AEM, p-type). The materials described in this project are uniquely multifunctional, combining the properties of nanoporosity, efficient exciton migration and charge transport, and strong interfacial interaction with the guest (target) molecules. We see this combination as enabling a range of important technological applications that demand tightly coupled interaction between matter, photons, and charge. Such applications may include optical sensing, electrical sensing, and polarized emission. Particularly, the well-defined nanowires fabricated in this study represent unique systems for investigating the dimensional confinement of the optoelectronic properties of organic semiconductors, such as linearly polarized emission, dimensionally confined exciton migration, and optimal pi-electronic coupling (favorable for charge transport). Combination of these properties will make the 1D self-assembly ideal for many orientation-sensitive applications, such as polarized light-emitting diodes and flat panel displays.     

木质素纳米颗粒的制备及其功能化应用研究进展

木质素是一种天然生物质资源,来源广泛,成本低廉。近年来,利用纳米技术将木质素制备成木质素功能化纳米颗粒极大推动了木质素的利用,同时显著解决了传统材料无法解决的突出问题。详细介绍了木质素功能化纳米颗粒的自组装法、机械法、聚合组装法、冻干炭化法等制备方法及其在催化剂、助剂、吸附剂、紫外防护和抗氧化、抗菌、载体材料、聚集诱导发光材料等领域的应用研究,展望了木质素纳米颗粒的应用前景。指出实现木质素纳米颗粒的可控制备、功能化修饰,将有利于推动木质素功能化纳米颗粒在环保、能源、催化和生物医学等领域的进一步应用。     

Self-Assembling Peptide-Based Functional Biomaterials

Peptides can self-assemble into various hierarchical nanostructures through noncovalent interactions and form functional materials exhibiting excellent chemical and physical properties, which have broad applications in bio-/nanotechnology. The self-assembly mechanism, self-assembly morphology of peptide supramolecular architecture and their various applications, have been widely explored which have the merit of biocompatibility, easy preparation, and controllable functionality. Herein, we introduce the latest research progress of self-assembling peptide-based nanomaterials and review their applications in biomedicine and optoelectronics, including tissue engineering, anticancer therapy, biomimetic catalysis, energy harvesting. We believe that this review will inspire the rational design and development of novel peptide-based functional bio-inspired materials in the future.     

Nanoparticles in Liquid Crystals: Synthesis,Self-Assembly,Defect Formation and Potential Applications

Revolutionary developments in the fabrication of nanosized particles have created enormous expectations in the last few years for the use of such materials in areas such as medical diagnostics and drug-delivery, and in high-tech devices. By its very nature, nanotechnology is of immense academic and industrial interest as it involves the creation and exploitation of materials with structural features in between those of atoms and bulk materials, with at least one dimension limited to between 1 and 100 nm. Most importantly, the properties of materials with nanometric dimensions are, in most instances, significantly different from those of atoms or bulk materials. Research efforts geared towards new synthetic procedures for shape and size-uniform nanoscale building blocks as well as efficient self-assembly protocols for manipulation of these building blocks into functional materials has created enormous excitement in the field of liquid crystal research. Liquid crystals (LCs) by their very nature are suitable candidates for matrix-guided synthesis and self-assembly of nanoscale materials, since the liquid crystalline state combines order and mobility at the molecular (nanoscale) level. Based on selected relevant examples, this review attempts to give a short overview of current research efforts in LC-nanoscience. The areas addressed in this review include the synthesis of nanomaterials using LCs as templates, the design of LC nanomaterials, self-assembly of nanomaterials using LC phases, defect formation in LC-nanoparticle suspensions, and potential applications. Despite the seeming diversity of these research topics, this review will make an effort to establish logical links between these different research areas.     

Hierarchically bimodal mesoporous silica fibers as building units for silica monolith with trimodal porous architecture

This work reports the controllable preparation of a unique kind of hierarchically mesoporous silica (HMS) fibers with bimodal porosities based on a simple TEOS/P123/HCl(aq.) templating system via the partitioned cooperative self-assembly (PCSA) process. Experimental results show that the formation of hierarchical mesostructures, especially the 2nd mode porous structure, depends on the interval time pertaining to the PCSA process. Synthetic conditions, including the interval time, temperature and stirring, are all found to be important in the evolution of fiber particle morphology. Moreover, such HMS fibers can be used as building units to prepare mesoporous silica monoliths with hierarchical trimodal pore systems via a simple gel-casting method, with additional (the 3rd modal) macropores originating from the packing of micron-sized HMS fibers. Such materials might further expand the application of both HMS fibers and HMS monoliths in various fields.     

Self-assembly of gold nanoparticles to silver microspheres as highly efficient 3D SERS substrates

Herein we report a simple, one-pot, surfactant-free synthesis of 3D Ag microspheres (AgMSs) in aqueous phase at room temperature. The 3D AgMSs act as supports to fix the gold nanoparticles (GNPs) in 3D space via the interaction between the carboxyl groups of GNPs and the Ag atoms of AgMSs. The ensemble of AgMSs@GNPs with high surface-enhanced Raman scattering (SERS) activity and sensitivity can be an ideal 3D substrate choice for practical SERS detection applications. The simple self-assembly strategy may be extended to other metallic materials with great potentials in SERS, catalysis, and photoelectronic devices.     

A Facile and Green Microwave-Assisted Strategy to Induce Surface Properties on Complex-Shape Polymeric 3D Printed Structures

Light- induced polymeric 3D printing is becoming a well-established fabrication method, showing manifold advantages such as control of the local chemistry of the manufactured devices. It can be considered a green technology, since the parts are produced when needed and with minimum amount of materials. In this work 3D printing is combined with another green technology, microwave-assisted reaction, to fabricate objects of complex geometry with controllable surface properties, exploiting the presence of remaining functional groups on the surface of 3D printed specimens. In this context, surface functionalization with different amines is studied, optimizing formulations, reaction times, and avoiding surface deterioration. Then, two different applications are investigated. MW-functionalized filter-type structures have been tested against Staphylococcus aureus bacteria, showing high bactericidal activity on the surface along all areas of the complex-shaped structure. Second, a fluidic chip composed of three separated channels is 3D printed, filled with different amine-reactive dyes (dansyl and eosine derivatives), and made to react simultaneously. Complete and independent functionalization of the surface of the three channels is achieved only after 2 min of irradiation. This study demonstrates that light induced 3D printing and microwave-induced chemistry can be used together effectively, and used to produce functional devices.     

基于3D打印技术制造柔性传感器研究进展

与传统的涂覆、沉积等加工手段相比,使用3D打印技术可制造复杂立体功能结构的传感器,将3D打印与柔性传感技术结合可以促进未来生物医疗、人工智能等领域的发展。本文介绍了国内外基于3D打印技术制造柔性传感器的最新进展,其中包括聚酰亚胺等多种基底材料、纳米金属等多种打印传感材料;按照熔融沉积、黏弹性墨水沉积、粉末烧结熔化、还原光聚合和材料喷射的制造原理分别阐述了多种传感器的材料选择、成型特点,并对制造方法进行总结分析。虽然3D打印制造柔性传感器件存在着缺乏行业标准及多种类打印材料等问题,但经过不断创新与发展,3D打印将成为柔性传感领域极佳的制造手段。     

Nanomaterials based on peptides

Owing to the assortment of functional groups, peptides are capable of self-assembly and formation of regularly patterned supramolecular complexes. Peptide-based nanomaterials offer promise for medicine, engineering, and bioimaging. The present review surveys the structure and characteristics of filaments formed by peptides of various secondary structures and their further assembly into 2D and 3D nanomaterials. Possible application areas of self-assembling peptide systems, including the synthesis of inorganic nanomaterials, are considered.     

基于二维纳米材料的水处理功能膜研究进展

二维纳米材料是制备膜材料中一类重要的掺杂材料或膜构筑单元,也是新型水处理功能膜的研究热点。已有许多研究报道了二维纳米材料通过有序的堆叠和自组装在膜内构建出规整的水通道,可以赋予膜可调控的分离性能,进而实现trade-off效应的突破,被认为是“下一代膜材料”（next-generation membranes）。同时,二维纳米材料的独特片层结构、催化性能及可修饰性可使膜材料获得新的功能,如导电性能、光/电催化性能等。本文综述了近年来基于二维纳米材料的水处理功能膜研究进展,重点介绍了共混法、自组装等制备方法,并总结了此类功能膜在抗污染、膜通量恢复、强化污染物去除、调控盐截留及污染物监测领域的应用。最后对基于二维纳米材料的水处理功能膜发展方向,如限域催化、调控盐分离、监测传感等新兴领域进行了分析和展望。     

纤维素化学研究进展

为了研究当前纤维素化学发展现状,综述了纤维素超分子结构及其成因,介绍了纤维素自组装的结构模型,讨论了纤维素的多种原材料（细菌纤维素、人工化学合成纤维素、棉花、木材、禾草植物、韧皮纤维以及农业废弃物）,着重介绍了细菌纤维素的制备与商业用途以及人工化学合成纤维素,综述了目前纤维素化学研究的热门课题：选择性取代、新纤维素溶剂、纤维素的预处理、纤维素衍生物以及纤维素功能材料的发展现状、再生纤维的研究发展现状、纳米纤维素的制备与表面化学改性.选择适宜的原材料,对天然纤维素进行可控物理、化学结构设计,从而可以制备特殊功能的精细化工产品.纤维素化学是21世纪可持续发展的化学工程研究的重要课题之一.     

Cytotoxicity screening of 23 engineered nanomaterials using a test matrix of ten cell lines and three different assays

Background

The most common causes of granulomatous inflammation are persistent pathogens and poorly-degradable irritating materials. A characteristic pathological reaction to intratracheal instillation, pharyngeal aspiration, or inhalation of carbon nanotubes is formation of epithelioid granulomas accompanied by interstitial fibrosis in the lungs. In the mesothelium, a similar response is induced by high aspect ratio nanomaterials, including asbestos fibers, following intraperitoneal injection. This asbestos-like behaviour of some engineered nanomaterials is a concern for their potential adverse health effects in the lungs and mesothelium. We hypothesize that high aspect ratio nanomaterials will induce epithelioid granulomas in nonadherent macrophages in 3D cultures.

Results

Carbon black particles (Printex 90) and crocidolite asbestos fibers were used as well-characterized reference materials and compared with three commercial samples of multiwalled carbon nanotubes (MWCNTs). Doses were identified in 2D and 3D cultures in order to minimize acute toxicity and to reflect realistic occupational exposures in humans and in previous inhalation studies in rodents. Under serum-free conditions, exposure of nonadherent primary murine bone marrow-derived macrophages to 0.5 μg/ml (0.38 μg/cm²) of crocidolite asbestos fibers or MWCNTs, but not carbon black, induced macrophage differentiation into epithelioid cells and formation of stable aggregates with the characteristic morphology of granulomas. Formation of multinucleated giant cells was also induced by asbestos fibers or MWCNTs in this 3D in vitro model. After 7-14 days, macrophages exposed to high aspect ratio nanomaterials co-expressed proinflammatory (M1) as well as profibrotic (M2) phenotypic markers.

Conclusions

Induction of epithelioid granulomas appears to correlate with high aspect ratio and complex 3D structure of carbon nanotubes, not with their iron content or surface area. This model offers a time- and cost-effective platform to evaluate the potential of engineered high aspect ratio nanomaterials, including carbon nanotubes, nanofibers, nanorods and metallic nanowires, to induce granulomas following inhalation.     

Stepwise Optimized 3D Printing of Arbitrary 3D Structures at Millimeter Scale with High Precision Surface

3D printing based on additive manufacturing has attracted widespread attention in the fields of microbiology and microelectronics due to its advantages of waste reduction, arbitrary manufacturing, and rapid prototyping in potential applications. These techniques can create structures at the centimeter scale, however, there are some limitations in terms of resolution and geometric constraints. Here, a micro–nano 3D printing protocol based on additive manufacturing to achieve the 3D structure (3DS) not only possessing millimeter scale structural dimensions but also nanometer features are proposed. A theory is verified to assist the design and fabrication of the 3DS with millimeter scale and nanometer precision. The structures are predesigned and the scanning strategy is optimized before 3D printing to improve the manufacturing efficiency and precision. A customized 3DS with a height of 2.2 mm is obtained, which is a challenge for the conventional two‐photon polymerization fabrication. Furthermore, a 1.2 mm 3DS with inside scaffold and smooth surface is efficiently achieved within 2.7 h with a nanometer surface roughness by using the proposed stepwise optimized 3D printing process. This study offers a flexible and low‐cost technology to generate highly customizable, precisely controllable 3DS for potential applications in microelectronics and microdevices.     

Smart nanomaterials inspired by biology: dynamic assembly of error-free nanomaterials in response to multiple chemical and biological stimuli

Three-dimensional functional nanoscale assembly requires not only self-assembly of individual nanomaterials responsive to external stimuli, such as temperature, light, and concentrations, but also directed assembly of many different nanomaterials in one-pot responsive to multiple internal stimuli signaling the needs for such materials at a specific location and a particular time. The use of functional DNA (DNAzymes, aptamers, and aptazymes) to meet these challenges is reviewed. In addition, a biology-inspired proof-reading and error correction method is introduced to cope with errors in nanomaterials assembly.     

一维贵金属纳米材料的控制合成与应用

一维纳米材料具有优良的尺寸效应,一维贵金属材料表现出不同于相应块体材料的特殊物理化学性能。本文以一维贵金属纳米结构的合成方法和机理为探讨重点,总结了近年来国内外用于控制合成一维贵金属纳米材料的主要方法,包括模板法、多元醇还原法、化学电沉积法以及金属催化还原法。着重以金属银、钯为例,介绍了其形状可控的一维纳米结构的生长机理,并以金、银等一维纳米材料为例介绍了其一维纳米结构在功能材料以及生物医学等领域的应用前景。指出建立一维金属纳米结构制备科学的新理论、新方法及其成核生长动力学模型是进一步研究的方向。     

Responsive nanostructures from aqueous assembly of rigid-flexible block molecules

During the past decade, supramolecular nanostructures produced via self-assembly processes have received considerable attention because these structures can lead to dynamic materials. Among these diverse self-assembly systems, the aqueous assemblies that result from the sophisticated design of molecular building blocks offer many potential applications for producing biocompatible materials that can be used for tissue regeneration, drug delivery, and ion channel regulation. Along this line, researchers have synthesized self-assembling molecules based on ethylene oxide chains and peptide building blocks to exploit water-soluble supramolecular structures. Another important issue in the development of systems that self-assemble is the introduction of stimuli-responsive functions into the nanostructures. Recently, major efforts have been undertaken to develop responsive nanostructures that respond to applied stimuli and dynamically undergo defined changes, thereby producing switchable properties. As a result, this introduction of stimuli-responsive functions into aqueous self-assembly provides an attractive approach for the creation of novel nanomaterials that are capable of responding to environmental changes. This Account describes recent work in our group to develop responsive nanostructures via the self-assembly of small block molecules based on rigid-flexible building blocks in aqueous solution. Because the rigid-flexible molecules self-assemble into nanoscale aggregates through subtle anisometric interactions, the small variations in local environments trigger rapid transformation of the equilibrium features. First, we briefly describe the general self-assembly of the rod amphiphiles based on a rigid-flexible molecular architecture in aqueous solution. We then highlight the structural changes and the optical/macroscopic switching that occurs in the aqueous assemblies in response to the external signals. For example, the aqueous nanofibers formed through the self-assembly of the rod amphiphiles respond to external triggers by changing their shape into nanostructures such as hollow capsules, planar sheets, helical coils, and 3D networks. When an external trigger is applied, supramolecular rings laterally associate and merge to form 2D networks and porous capsules with gated lateral pores. We expect that the combination of self-assembly principles and responsive properties will lead to a new class of responsive nanomaterials with many applications.     

Examination of Surfactant Protein D as a Biomarker for Evaluating Pulmonary Toxicity of Nanomaterials in Rat

This work studies the relationship between lung inflammation caused by nanomaterials and surfactant protein D (SP-D) kinetics and investigates whether SP-D can be a biomarker of the pulmonary toxicity of nanomaterials. Nanomaterials of nickel oxide and cerium dioxide were classified as having high toxicity, nanomaterials of two types of titanium dioxides and zinc oxide were classified as having low toxicity, and rat biological samples obtained from 3 days to 6 months after intratracheal instillation of those nanomaterials and micron-particles of crystalline silica were used. There were different tendencies of increase between the high- and low-toxicity materials in the concentration of SP-D in bronchoalveolar-lavage fluid (BALF) and serum and in the expression of the SP-D gene in the lung tissue. An analysis of the receiver operating characteristics for the toxicity of the nanomaterials by SP-D in BALF and serum showed a high accuracy of discrimination from 1 week to 3 or 6 months after exposure. These data suggest that the differences in the expression of SP-D in BALF and serum depended on the level of lung inflammation caused by the nanomaterials and that SP-D can be biomarkers for evaluating the pulmonary toxicity of nanomaterials.     

Self-Assembly of Optical Molecules with Supramolecular Concepts

Fabrication of nano-sized objects is one of the most important issues in nanoscience and nanotechnology. Soft nanomaterials with flexible properties have been given much attention and can be obtained through bottom-up processing from functional molecules, where self-assembly based on supramolecular chemistry and designed assembly have become crucial processes and techniques. Among the various functional molecules, dyes have become important materials in certain areas of nanotechnology and their self-assembling behaviors have been actively researched. In this short review, we briefly introduce recent progress in self-assembly of optical molecules and dyes, based mainly on supramolecular concepts. The introduced examples are classified into four categories: self-assembly of (i) low-molecular-weight dyes and (ii) polymeric dyes and dye self-assembly (iii) in nanoscale architectures and (iv) at surfaces.     

Self-Assembly of Cholesterol-Doxorubicin and TPGS into Prodrug-Based Nanoparticles with Enhanced Cellular Uptake and Lysosome-Dependent Pathway in Breast Cancer Cells

Developing new easy-to-prepare functional drug delivery nanosystems with good storage stability, low hemotoxicity, as well as controllable drug delivery property, has attracted great attention in recent years. In this work, a cholesterol-based prodrug nanodelivery system is prepared by self-assembly of cholesterol-doxorubicin prodrug conjugates (Chol-Dox) and tocopherol polyethylene glycol succinate (TPGS) using thin-film hydration method. The Chol-Dox/TPGS assemblies (molar ratio 2:1, 1:1, and 1:2) are able to form nanoparticles with average hydrodynamic diameter of ≈140–214 nm, surface zeta potentials of ≈−24.2–−0.3 mV, and remarkable solution stability in 0.1 m PBS, 16 days). The Chol-Dox/TPGS assemblies show low hemotoxicity and different cytotoxicity profiles in breast cancer cells (MCF-7 and MDA-MB-231), which are largely dependent on the molar ratio of Chol-Dox and TPGS. The Chol-Dox/TPGS assemblies tend to enter into MCF-7 and MDA-MB-231 cells through non-Clathrin-mediated multiple endocytosis and lysosome-dependent uptake pathways, moreover, these nanoassemblies demonstrate lysosome-dependent intracellular localization, which is different from that of free DOX (nuclear localization). The results demonstrate that the Chol-Dox/TPGS assemblies are promising cholesterol-based prodrug nanomaterials for breast cancer chemotherapy. Practical Applications: This work demonstrates a lipid prodrug-based nanotherapeutic system. Herein the Chol-Dox/TPGS nanoassemblies could serve as promising and controllable cholesterol-based prodrug nanomaterials/nano-formulations for potential breast cancer chemotherapy.     

Triboelectrification of particulate flows on surfaces: Part II — Mechanisms and models

Triboelectric charge accumulation both poses problems and offers opportunities for dry particulate processing. It generates hazards in many industrial systems, but is exploited in several important applications, including electrophotographic toner charging and triboelectric separation. However, the charging of continuous particulate flows on solid surfaces is poorly understood, and design of devices to optimise triboelectric behaviour is often qualitative or based on trial and error. This study attempts to identify the main charging mechanisms for a continuous particulate flow on a flat surface. The proposed charging models incorporate contact time, velocity and mode of contact. A model incorporating contact area effects arising from sliding and rolling contact is consistent with experimental data, as long as a charge limit is imposed on bouncing particles. A mechanism for this charge limit, involving separation discharge, is proposed. The effect of delocalised image charge on the system is estimated and found to be negligible. Some general design principles are proposed for triboelectric optimisation of particle processing devices.